Treatment of oils



Patented Oct. 18,193;

nrrrn STATES PATENT? oi-Pics JOSEPH BENNETT HILL, OF WYNNEWOOD, PENNSYLVANIA, JASSIGNOR TO THE ATLANTIC REPINING COMPANY, OF PHILADELPHIA, PENN SYLYANIA, A CORPORATION OF PENNSYLVANIA rnmrrrnlvr or OILS No Drawing.

The present invention relates to the art ofmineral oil refining, and has particular reference to the separation of crude petroleum .or petroleum products into fractionsof diiferent chemical compositions while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscosity, are separated into various fractions by means of fractional extraction with furfuryl alcohols, or mixture of solvents containing substantial quantities of furfuryl alcohols.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as parafiins of the general formula C I-1 olefines of the general formula C H hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely paraffinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in diflerent proportions. -.For example, in the p'araflin base crude oils, such as those obtained from the oil fields of Pennsyl vania, there is a relatively high proportion of hydrocarbons having a chain structure and a characteristics.

Application filed May 21,

specific gravity to the viscosity of one oil as compared with another. For, example, oils derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 R, will show a specific gravity at F., of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf coast area, will show .a specificgravity of about 0.933 at 60 F. .The relationship be tween the viscosity and gravity indicates the degree of the paraflinic or naphthenic character of the oi If given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of the several fractions determined, it will be found that they conform to the general relationship:

in which G is the specific gravity at 60 F.,

log (V-38) V is Saybolt universal viscosity at 100 F., and a is a constant known as the viscositygravity constant. Fractions from each of the different types of crudehave different vis cosity-gravity constants. Such constants are lower for fractions of the paraflinic crudes than are the constants for fractions of the naphtheniccrudes. Anarticle entitled The viscosity-gravity constant of petroleum lubrieating oils by J. B. Hill and H. B. Coats, which willbe found in volume 20, page 641 et seq., Industrial and Engineering Chemistry for June,i'l928fexplains the determination. of such constant for several typical oils.

The viscosity-gravity constant is, therefore, 7

an index of the parafiinicity or naphthenicity of an oil, since when a given crude is distilled and fractions thereof are collected re ardless of the fraction upon which the speci c gravity and theviscosity are taken, when suchspecific gravity and viscosity are substituted in the formula and the viscosityavity constant of the fraction calculated, he constant to obtain from an oil containin will be substantiall the same for each of the several fractions 0 the crude.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) O. 8367 Guadalupe (Gulf Coast) 0. 8635 Mirando (Gulf Coast) 0. 9025 The various series of hydrocarbons possess a difierentialsolubility in such solvents; the naphthenic h drocarbons are much more soluble therein than the parafiinic hydrocarbons. By means of extraction with furfu l alcohols and more particularly with fur uralco hol (CJLOfiH OH), it is, therefore, possible to effect a partial separation of the naphthenic hydrocarbons from the paraflinic, and both classes of hydrocarbons, an oil which is much more parafiinic than the original oil and one which 18 much more naphthenic. By my invention, for example, it 1s possible to produce an oil palachian crudes, from crudes of the mixed asetype from the Mid-Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf coast area.

In practicing my invention, 1. refer to mix the oil fraction to be treate with a suitable proportion of furfuryl alcohols, and more particularly with furfuralcohol (CLH QCH OH) at a temperature sufficiently high so that complete solution is efl'ected and a homogeneous liquid obtained. I then 0001 the mixture toa temperature suflicientlylow to cause a separation of the liquid into a two-layer system, the upper layer being a solution of a relatively small amount of the furfuralcohol in the more paraifinic portion of the oil,-and the lower layer comprising a solution of the more naphthenic portion of the oil in the furfuralcohol. Instead of this heating and cooling to effect extraction, I may simply agitate themixture of liquids at normal temperatures. Where substantial uantities of solid hydrocarbons belonging to t e true paraflin ser1es (CnH are present,

' these solids or waxes remain in the upper layer and may cause it to be solid or semiso id. Separation of the two layers in then from the following specific example:

of the quality normally obtained from Ap effected-for example, by decantation, and the furfuryl alcohol removed from each of the separated-oil layers b vacuum distillation or other suitable proce ure, thereby obtaining two oils of similar distillation ranges but of, '70 widely difierent physical characteristics and correspondingly different chemical compositions. 4

Before removing the furfuryl alcohol from the upper and more paraflini'c layer of oil obtained in the above described process, I may add a further quantity of furfuryl alcohol, and repeat the process for an extraction of additional naphthenic bodies from the oil. The extraction may be repeated any desired number of times, thereby producing oils of progressively increasing parafiinicity as evidenced by a decreasing viscosity-gravity constant. In wax-bearing oils, the final undissolved product is a mixture of solid and liquid hydrocarbons. While the exact chemical compositions of these compounds are not known, it is probable that the liquid hydrocarbons are branched chain hydrocarbons of the paraflin series, whereas solid bodies are straight chain arafiin hydrocarbons. This product may be lirther separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes, such as the cold settling process.

, 'In many instances it will be found of advantage to dewax the oil prior to the extraction process, as this expedites the manual operation of the latter.

My invention will be further understood 100-parts of a previously untreated distillate obtained from a Gulf coast crude oil and having a viscosity of 612 seconds Saybolt universal at 100 F., a specific gravity of 0.9303 and a consequent viscosity gravity constant of 0.874 was mixed with. 300 parts of furfuralcohol (G4HQO.CHZOH) and heated to slightly'above the temperature of complete miscibility, which in the particular case was approximately 152 C. The homogeneous liquid which resulted was cooled with agitation to 1 125 0., and allowed to settle whereupon a two layer system formed, which consisted of an upper undissolved oil layer comprising 56.9 parts of'the mixture and a lower layer of oil dissolved in furfuralcohol' comprising approximately 3431 parts of themixture. After separation, the layers were each freed from furfuralcohol by vacuum distillation. The undissolved fraction yielded 10.5 parts of furfuralcohol and 46.4 parts of an oil. having a viscosity of 439 seconds Saybolt universal at 100 F., and a specific gravity of 0.9007, and a viscosity gravity constant ofv 0.839.

From the above example it will be seen that by a furfuralcohol extraction there may be obtained oil fractions which are respec- 'tively higher in paraifinicity and naphthenicity than the original oil. By repetition of the extraction process upon the furfur- 0 alcohol undissolved fraction, oils may be obtained. which are increasingly paraflinic, as evidenced by progressively decreasing viscosity-gravity constants.

It is evident that my process is practically independent of the particular nature or source of the crude oil, and that there may be produced thereby oils of desired characteristics from oils which heretofore have not been used as a source of oils of such desired characteristics.

For example, my process may be employed to produce from petroleum of a mixed base type such as would, on normal batch distillation, give a residuum'with a viscosity of 150 seconds Saybolt universal at 210 F. with a specific gravity of 0.928 or more, a lubricating 7 stock with a viscosity of 150 seconds Saybolt universal at 210 F., or more, and a specific gravity not higher than 0.910. This latter combination of properties is typical of cylinder stocks produced from Pennsylvania crudes.

In extracting oils containing appreciable amounts of wax, such oils may be dewaxed, for example, by cold settling or centrifuging prior to carrying out the extraction. My process is operable, however, in the absence of preliminary dewaxing.

Hereinabove, mixtures of solvents have been referredto. It is to be understood that in such mixtures the constituent solvents will not react with one another, nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts of furfuryl alcohols. I

For brevity, in the appended claims, the

term furfuryl alcohol is employed in a generic sense to include one or a mixture of furfuryl alcohols, or a mixture of solvents which contains substantial quantities of furfuryl alcohols. Also where herein and in the appended claims, an oil is specifically referred to as being viscous, it is to be understood that the oil is of substantial viscosity, i. e., of the order 'of seconds Saybolt universal at 100 F., or more.

What I claim is:

1. In'the art of refining mineral oils, the process which comprises separating an oil containing parafiinic and naphthenic hydrocarbons into fractions respectively richer in paraflinic and naphthenic compounds by extracting said oil with furfuryl alcohol.

2. In the art of refining mineral oils, the process which comprises fractionally extracting an oil containing paraflinic and naphthenic hydrocarbons with furfuryl alcohol to produce fractions of the oil respectively richer in parafiinic and naphthenic compounds. i I

3. In the art of refining mineral oils, the process which comprises adding furfuryl alcohol to an oil containingparaifinic and naph- ..05,thenic hydrocarbons, heatingthe mixture to such temperature as to'efiect solution, cooling the solution to form a two layer system, and.

separating the upper layer from the lower layer.

4. In the art of refining mineral oils, the process which comprises adding furfuryl alcohol to an oil containing paraflinic and naphthenic hydrocarbons, heating the mixture to such temperature as to efi'ect solution, cooling the solution to form a two layer system, removing the lower layer, and similarly retreating the upper layer with furfuryl alcohol.

5. In the art of refining mineral oils, the process which comprises bringing a mineraloil containing paraflinic and naphthenic hydrocarbons into contact with furfuryl alcohol, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the furfuryl alcohol, separating the solution so formed from the remainder of the oil, and removing the furfuryl alcohol from both portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

6. The process for separating mineral oils containing parafiinic and naphthenic hydrocarbons into fractions which comprises bring, ing the oil into contact with furfuryl alcohol, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the furfuryl alcohol, separating the solution so formed from the remainder of the oil, and

distilling the 'furfuryl alcohol from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in paratfinic and naphthenic hydrocarbons.

7. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contactFwith furfuryl alcohol, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the furfuryl alcohol, separating the solution so formed from the remainder of the oil, and retreating the oil remaining with additional amounts of furfuryl alcohol.

8. The method of producing paraflinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact with furfuralcohol, thereby partially dissolving the oil, separatingthe furfuralcohol solution of oil so treated, and removing the furfuralcohol from the treated oil.

9. The process of producing a lubricating stock of specific gravity less: than .910 and of Saybolt universal viscosity greater than 150 seconds at 210 F. from a crude petroleum which on normal distillation yields a residuum of 150 seconds Saybolt universal viscosity at 210-F. and a specific gravity greater than .928, which comprises producing a residuum from the crude petroleum, and extracting said residuum from said crude pe-the rocess which com troleum with furfuralcohol. a

10. In the art of refining mineral lubricating oil containing parafiinic and naphthenic hydrocarbons, the step of fractionally extracting the oil with furfuralcohol, to effect a separation of fractions respectively richer in paraifinic and naphthenic compounds.

11. The process of producing a lubricating stock of specific gravity less than ..91O and of Saybolt universal viscosity greater than 150 seconds at 210 F. from a crude petroleum which on normal distillation yields a residuum of 150 seconds Saybolt universal viscosity at 210 F. and a specific gravity greater than .928, which comprises separating a residuum lifrom said crude petroleum and bringing such residuum into contact with furfuralcohol, to effect solution of 'a portion thereof with the furfuralcohol, separating the furfuralcohol solution of oil from theportion which does not dissolve therein, and removing the furfuralcohol from the oil of said solution.

12. In a process for separating a viscous mineral oil containing parafiinic andnaphthenic hydrocarbons into fractions which are respectively richer in naphthenic hydrocarbon and parafiinic hydrocarbons other than wax, the step which comprises extracting the oil with furfuralcohol.

13. In a process for separating viscous mineral oil liquid at ordinary temperature containing paraffinic and naphthenic hydrocarbons into fractions respectively richer in parafi'inic and naphthenic hydrocarbons, the

step which comprises extracting the oil with furfuralcohol.

14. In a process for separating a substantially wax free viscous mineral oil containing p'araflinic and naphthenic hydrocarbons into fractions respectively richer in parafiinic and naphthenic hydrocarbons, the step which comprises extracting the oil with furfuralcohol. Y

15. The process of treating a viscous fraction of a crude oil of one type containing paraflinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of paraifinic hydrocarbons, which comprises extracting the viscous fraction with furfuralcohol, and separating the oil so treated into portions respectively richer in paraflinic and lnaphthenic hydrocarbons.

16. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having -the quality of a corresponding fraction of, a paraffinic base crude, which comprises extracting the viscous fraction with furfuralcohol, and separating the oil so treated into portions respectively richer in paraflfinic and naphthenic compounds.

17. In the art of refining mineral oils,

prises adding furfuralco 01 to a viscous 011 liquid at ordinary temperatures containin parafiinic and naphthenic hydrocarbons, heating the mixture to a temperature sufiicient to effect solution, cooling the solution to a temperature suf ficient to form two layers respectively richer in naphthenic hydrocarbons and parafiinic hydrocarbons other than wax, and separating the upper layer richer in paraflinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

18. In the art of refining mineral oils, the

process which comprises adding furfural- DiscLA ME-fifi 1,883,374.-J0seph Bennett Hill, Wy nnewood,"Pa., TR ATMENT or Onis. Patent dated October 18, 1932. Disclaimer filed January 17, 1934, by theassigne'e,

The Atlantic Refining Company.

Hereby enters this disclaimer, to wit: Petitioner disclaims from the scope of claims 1 to 7 inclusive of the aforesaid patent, processes which employ fnrfurylalcohols, the furane ring of which is wholly. or partially saturated, e. g., and not by way of limitation, tetrahydrofurfuryl alcohol but without disclaiming fnrfuryl alcoholsin which the furane ring,

remains intact, or in other words, in which the two double bonds Between carbons of the ring remain unbroken.- [Ofllc'lal Gazette February'', 1.984. 

